RGD Reference Report - Laminin alpha 3 forms a complex with beta3 and gamma3 chains that serves as the ligand for alpha 6beta1-integrin at the apical ectoplasmic specialization in adult rat testes. - Rat Genome Database

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Laminin alpha 3 forms a complex with beta3 and gamma3 chains that serves as the ligand for alpha 6beta1-integrin at the apical ectoplasmic specialization in adult rat testes.

Authors: Yan, HH  Cheng, CY 
Citation: Yan HH and Cheng CY, J Biol Chem. 2006 Jun 23;281(25):17286-303. Epub 2006 Apr 11.
RGD ID: 1600017
Pubmed: PMID:16608848   (View Abstract at PubMed)
DOI: DOI:10.1074/jbc.M513218200   (Journal Full-text)

Apical ectoplasmic specialization (ES) is a testis-specific hybrid cell/cell actin-based adherens junction and cell/matrix focal contact anchoring junction type restricted to the interface between Sertoli cells and developing spermatids. Recent studies have shown that laminin gamma3, restricted to elongating spermatids, is a putative binding partner of alpha 6beta 1-integrin localized in Sertoli cells at the apical ES. However, the identity of the alpha and beta chains, which constitute a functional laminin ligand with the gamma3 chain at the apical ES, is not known. Using reverse transcription-PCR and immunoblotting to survey all laminin chains in cells of the seminiferous epithelium, it was noted that alpha 2, alpha 3, beta1, beta2, beta3, and gamma3 chains were found in germ cells, whereas alpha 1, alpha 2, alpha 4, alpha 5, beta1, beta2, gamma1, gamma2, and gamma3 chains were found in Sertoli cells, implying that alpha 3 and beta3 are the plausible laminin chains restricted to germ cells that may be the bona fide partners of gamma3. To verify this postulate, recombinant proteins based on domain G of alpha 3 and domain I of beta3 and gamma3 chains were produced and used to obtain the corresponding specific polyclonal antibodies. Additional studies have demonstrated that the laminin alpha 3, beta3, and gamma3 chains indeed are restricted to germ cells at the apical ES, co-localizing with each other and with beta1-integrin. Furthermore, co-immunoprecipitation studies have confirmed the interactions among laminin alpha 3, beta3, and gamma3, as well as beta1-integrin. When the functional laminin ligand at the apical ES was disrupted via blocking antibodies, such as using anti-laminin alpha 3 or gamma3 IgG, this treatment perturbed adhesion between Sertoli and germ cells (mostly spermatids), leading to germ cell loss from the epithelium. More important, a transient disruption of the blood-testis barrier was also detected.

Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
cell-cell adhesion  IMP 1600017 RGD 

Cellular Component
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
adherens junction  IDA 1600017; 1600017 RGD 

Molecular Function

Objects Annotated

Genes (Rattus norvegicus)
Itga6  (integrin subunit alpha 6)
Lama3  (laminin subunit alpha 3)
Lamb3  (laminin subunit beta 3)


Additional Information